Heat the olive oil in a large pot over medium heat. Add the onion and cook until soft and lightly golden.
Stir in the garlic, red and green bell peppers, and cook for about 5 minutes until slightly tender.
Mix in tomato paste, cumin, smoked paprika, and cayenne pepper. Let it toast for a minute to bring out the flavor.
Add the diced tomatoes, mixed beans, and vegetable broth. Stir well and bring it to a gentle boil.
Lower the heat and let it simmer uncovered for about 30 minutes, stirring occasionally until thickened.
Taste and adjust seasonings with salt and pepper before serving.